Three projects are planned: 1) a continuation of studies of factors that control the stability of key glycolytic enzymes. Reversible inactivation controlled by substrates and effectors and evidence for arsenite sensitivity as a common feature of these enzymes will be tested. 2) Determine the mechanism of hexokinase activation of deoxyglucose uptake in serum stimulated chick embryo fibroblasts; and 3) examine the possibility that the prolonged glucose intolerance of cancer-bearing subjects is caused by a depletion of serum factors responsible for hexokinase activation.